The injection of chemicals in order to enhance the production of hydrocarbon products from a well, has long been practiced. Many types of pumps have been used. It is desirable to provide a discreet amount of chemical, withdrawn from a source, at regular intervals, to a production well. Obviously other operations than production wells may have such needs. Various problems have occurred. Applicants' prior copending application dealt with the prevention of contamination of or by the injection fluid, by using 2-way seals around a reciprocating plunger. A particular problem addressed by this invention, is the excessive amount of energy necessary to cause pump plunger reciprocation, and the excessive wear, and thereby cost of operation. Applicants have attempted to solve this problem by providing a low friction mechanism for reciprocating said plunger.